The present invention relates to four-wheel drive vehicles in general and more particularly to a plural path torque transfer mechanism for such a vehicle.
It is well known in the art that the tractive effort of a vehicle is substantially improved if driving torque is applied to both front and rear axles. This concept has long been used in military and off-highway vehicles by providing a torque transfer mechanism between the axles. The torque transfer mechanism includes means for receiving torque from a prime mover and delivering this torque to the axles.
Four-wheel drive systems of this general type are known which provide a plurality of power paths through the torque transfer mechanism. In one instance this has been accomplished through the use of a pair of chain drive power paths, such as shown in U.S. Pat. No. 830,642 issued Sept. 11, 1906 to Chaquette. Another accomplishes this result by employing a pair of gear drive power paths such as shown in U.S. Pat. No. 2,203,282 issued to Keese, June 4, 1940.
While these arrangements have provided the desired plural power paths for a four-wheel drive vehicle, each unit involves certain compromises in size, ruggedness and quietness limiting their appeal. In particular the prior art devices have been either all chain drive or all gear drive resulting in large overall units and relatively noisy high speed operation respectively. In addition the construction details of the known prior art are not suited to ready manufacture.
It is, therefore an object of the present invention to substantially eliminate the compromises which have existed for decades in four wheel drive transfer case design.
Another object of the present invention is to provide a torque transfer mechanism wherein the housing is designed in such a manner as to permit the drive units to be pre-assembled and easily and conveniently mounted within the housing as subassemblies.
A further object of this invention is to provide a simple control system for selecting the desired power path through the torque transfer mechanism.
Still another object is to provide an improved mounting arrangement for the input and output means of the torque transfer mechanism which will prevent undesirable operation of the various parts under different load applications.